Hello Frank, sorry for the late reply. HDMI stays black, but I can’t find the cables for my UART adapter, so I cannot properly test. I think you are doing it right, but if what used to work does not, perhaps an easier way would be to copy the rock64.scm image, and adapt that to use the Beaglebone Black’s u-boot and the kernel linux-libre-arm-generic instead of linux-libre-arm64-generic, then pass this file to guix system image. But perhaps this still is the wrong kernel and you need an older kernel, either as an old linux-libre-arm-generic-4.19 kernel or an old kernel via a Guix inferior.
Regards, Florian
